Now they do, but originally all the blurays were mpeg2, it was part of the discussion around quality, and the vc1 codec was used on most HDDVDs vs MPEG2 on blurays nullifying the bitrate differences. IIRC of course, since i'm lazy.
No, you're wrong. The first blu-ray players had support for all those codecs. The first few mastered blu-ray discs were MPEG-2 encoded, but that was because the encoders were more mature at that point.
